Vibration dampener for vacuum tubes



Dec. 18, 1928 1,695,600

H. E. METCALF I VIBRATION DAMPENE IR FOR VACUUM TUBES Filed March 23, 1927 HERBERT E ME'TCALF uh BY I mu 1 7 INVENTORI ATTORNEYS.

I Patented Dec. 1a, 1928.

UNITED STATES PATENT OFFICE.

HERBERT E. METCALIF, OF SAN LEAN DRO, CALIFORNIA, ASSIC'NOR TO THE MAGNAVOX COMPANY, 01' SAN JFBANCISCO, CALIFORNIA, A CORPORATION OF ARIZONA.

VIBRATION DAMPENER FOR VACUUM TUBES.

Application filed March 23, 1927. Serial No. 177,591.

This invention relates to a vibration dampener for vacuum tubes such as three electrode tubes and especially to a filament support which will have a low period of vibration. The object of the present invention 15 to generally improve and simplify the con-. struction and operation of filament supports such as employed in three electrode vacuum tubes and the like; to provide a filamentsupport which will have a low period of vibration; to provide a filament support of a length longer than could be ordinarily employed; to provide a filament support of such flexibility that it will vibrate in resonance with low periods only and dampen completely the high periods of vibration and further to provide a three electrode vacuum tube 'in which the vibration dampener is built within the tube. The invention is shown by way of illustration in the accompanying drawings in which:

Fig. 1 is a'sectional view of a vacuum tube partially broken awayvshowing one form of the filament support.

Figs. 2 and 3 are similar views showing other forms of filament supports,

Fig. 4 is an enlarged detail view of the sleeveto whichthe filament support 1s secured.

The present invention provides a sleeve or bushing such as indicated at 2 set lIll'O the stem 3 of the tube with a filament support in the form of a wire or rod such as indicated at 4 welded or otherwise attached at a point adjacent the lower end of the sleeve as indicated at 5. By securing the filament support 4 in the manner illustrated, the support may be substantially twice as long as the leg of the filament indicated at 6 and as such will permit a low period of vibration. As all vibrations, either mechanical or a1r vibrations on the wall of the tube must pass u the filament support, the natural period 0? the support belng very low, all higher vibrations are efi'ectively dampened.

When using a sleeve such as here indicated, a lively or springy filament support is obtained because the rod or wire 4 is guarded from movement in all directions by indicated at 4 is secured by passing it through thesleeve or guard 2 and it is then embedded in the glass as indicated at 7 In Fig. 3 the filament support or rod indicated at 4' is welded to the sleeve 2 or it may be embedded in the glass at the lower end of the sleeve as shown in Fig. 2, the rod being in this instance Ipreferably oflset as indicated at 8 and a ook-shaped support 9 be- 1ng welded or otherwise secured at the upper end of the rod as indicated at 9 to su port the filament. The several forms disc osed all serve the same function, to wit, that of providin a filament support of considerable length w ich will not respond to the higher vibrations and these are accordingly efiectively dampened out.

While the present invention has been described in connection with vacuum tubes of the three electrode type, it is obvious that other applications are possible. It is for this reason that no description or illustration of the plate and grid has been resorted to.

While certain features of the present invention are more or less specifically described and indicated, I wish it understood that various changes may be resbrted to within the scope of the appended claims; similarly, that the materials and finish of the several parts employed may be such as the manufacturer may dictate or varying conditions or uses may demand.

Having thus described my I claim and desire to secure ent is 1. In a vacuum tube a hollow metal sleeve sealed into the stem of the tube and a filament support secured at a point adjacent the lower end of the sleeve.

2. In a vacuum tube a hollow metal sleeve sealed into the stem of the tube, an elongated filament support extending downwardly through the sleeve and centrally thereof and an offset portion on the filament support adapted to be welded to the lower end of the sleeve.

3. In a vacuum tube a hollow metal sleeve sealed into the stem of the tube, a rod-like filament support extending downwardly through the sleeve and centrally thereof, means securing the lower end of the rod with relation to the lowerend of the sleeve, said rod-like filament support being free to vibrate interiorly of the sleeve and being supinvention, what by Letters Patexcess vibration or movement of the tube at a point below that at-which y the inner wall of the sleeve. other electrode supports are attached. 1'

4. A vacuum tube having a stem, there be-' 6. A tube of the'characterde'scribed, having a depression in said stem, an elongated ing a stem, a metallic sleeve sealed the 15 6 filament support secured at a point adjacent stem, a rodlike filament support extending the bottom of the depression, and extending downwardly through the sleeve and disposed outwardly-therefrom. a centrally thereof, and means to secure said 5. In a vacuum tube a non-microphonic filfilament support adjacentt'he'of the ament'su port'con'structed so as to be sensisleeve. Y "1 10 tive to a ow'period of vibration-only, said p j filament support being attached to the stem HERBERT E. METCALF. 

